This invention relates generally to microcellar packet communication systems, and in particular to techniques for selecting a directional antenna of a plurality of directional antennas in a microcellar network device.
As personal wireless communication systems such as in cellular telephony proliferate, the spectrum available to the wireless user for accessing cell sites for interactive communication becomes premium. There is great pressure to shrink the cell size of cellular telephone systems, for example, in order to promote frequency reuse and ultimately increase user density and capacity, as well as to reduce the required transmitter power for battery-operated portables. This is part of the trend toward so-called microcellar systems.
An example of a microcellar system is described in U.S. Pat. No. 5,479,400, Robert P. Dilworth, et. al., entitled xe2x80x9cTransceiver Sharing Between Access and Backhaul in a Wireless Digital Communication System,xe2x80x9d issued Dec. 26, 1995, which is incorporated herein by reference. A network device in such a microcellar system may use an omni-directional or directional antennas. Using directional antennas on a remote network device that may be mounted on an elevated structure, for example a poletop, has the advantage of favoring signals in the selected direction and suppressing or rejecting other signals. To take advantage of the use of directional antennas, there is a need for a technique that selects the best antenna for a particular signal source.
According to the invention a method and a system are provided to determine and thus select the best choice for antenna to be used by a network device having a plurality of directional antennas for a particular sending source. The determination is made using on a metric based on the success rate of packets received at a particular directional antenna from the sending source and secondarily on a received signal strength indicator. The determination is stored and made available for processing such that a router is able to request communication through a device with a destination via the second wireless communication device without knowledge of the best antenna match.
An embodiment according to the invention provides a communication system having a plurality of directional antennas associated with a first communication device at a first site, a router for targeting a destination via an indeterminate path including the first site, at least one second wireless communication device at a second site, a method for selecting a best antenna from the plurality of directional antennas for the first wireless communication device for communicating with each second wireless communication device. The first communication device broadcasts packets, via each of the directional antennas, to query for the existence of the second wireless communication devices. The first device then receives a plurality of information packets about existence of the second wireless communication devices in response to the broadcast packets or in response to a query about third parties. Thereafter, as between each directional antenna and each second wireless communication device, a packet success metric is determined for each directional antenna. The packet success metrics are compared with each other to determine a best match of directional antenna with each second wireless communication device. The best match is stored at the first device such that the router is able to request communication through the first device with the destination via the second wireless communication device without knowledge of the best match. In the comparison, if there are two or more possible largest packet success numbers, then selecting the best number as the possible packet success is based on the largest number with a best Received Signal Strength Indication (RSSI) value.
Another embodiment provides a method for selecting a best antenna from a plurality of directional antennas at a remote device for communicating with a wireless access device at a wired access point having a plurality of wireless access devices, where the remote device and the wireless access device belong to a path determined by a router. Next a plurality of synchronization packets is sent and a response received from the wireless access device at the wired access point to determine the presence of wireless access devices at the wired access point. If a memory of the remote device includes a stored RSSI associated with the wireless access device, the remote device obtains a new RSSI associated with the wireless access device. The remote device compares the stored RSSI with the new RSSI to determine if the stored best antenna value is the best antenna for the wireless access device, where the determination is made independently of the router.
In an embodiment a system for selecting the best antenna at a remote device of a plurality of remote devices for communicating with a wireless access device of a wired access point of a plurality of wireless access devices is provided. Each wireless access device includes a wireless communication link for communication to the remote device and a wired communication link to a wired network. The system includes: means for sending a plurality of information packets from the wireless access device to the remote device; the remote device, comprising a processor, a memory, and a plurality of directional antennas for receiving the plurality of information packets, where the memory has stored software having: a signal quality evaluation module for determining a first quality metric for each directional antenna from the information packets received for that antenna; and an antenna selection module for selecting, based on the first quality metric, the best antenna for the wireless access device.
A further understanding of the nature and advantages of the inventions herein may be realized by reference to the remaining portions of the specification and the attached drawings.